Glossary

TLS

TL;DR

TLS (Transport Layer Security) is a cryptographic protocol that provides secure communication over the internet, replacing the older SSL protocol as the current standard for web security.

Concept

TLS (Transport Layer Security) is a cryptographic protocol designed to provide secure communication over a computer network. It’s the successor to SSL (Secure Sockets Layer) and is the current standard for securing internet communications, including web browsing, email, messaging, and API calls.

Key features and concepts of TLS include:

  1. Encryption: TLS encrypts data transmitted between clients and servers, preventing eavesdropping and unauthorized access.

  2. Authentication: TLS certificates verify the identity of communicating parties, typically through X.509 certificates issued by trusted Certificate Authorities.

  3. Data Integrity: TLS ensures that data has not been modified during transmission through cryptographic checksums.

  4. Handshake Protocol: A process that negotiates encryption algorithms, authenticates parties, and establishes shared encryption keys before data exchange.

TLS operates through two main layers:

  • Record Protocol: Handles packet segmentation, compression, encryption, and authentication of data
  • Handshake Protocol: Negotiates security parameters and authenticates the communicating parties

TLS versions include:

  • TLS 1.0: Released in 1999 as SSL 3.0’s successor
  • TLS 1.1: Released in 2006 with minor security improvements
  • TLS 1.2: Released in 2008 with significant security enhancements
  • TLS 1.3: Released in 2018 with improved security and performance

Key improvements in TLS 1.3 include:

  • Faster connection establishment (0-RTT resumption)
  • Removal of vulnerable cipher suites
  • Improved forward secrecy
  • Simplified handshake process

TLS is commonly used for:

  • Securing web traffic (HTTPS)
  • Email encryption (SMTPS, IMAPS, POP3S)
  • VPN connections
  • API security
  • File transfer security (FTPS, SFTP)

Organizations implement TLS to protect sensitive data in transit, comply with security regulations, build user trust through browser security indicators, and prevent man-in-the-middle attacks. It’s a fundamental requirement for modern web applications and services.

Related words: SSL HTTPS VPN